And a hood would help, too. WIth a deeper hood only the most directly head-on paintball shot might get to the protective filter. A wider hood would give less protection, but still would offer some. Photographing paintball and using a valuable lens, I'd use both... protection filter and hood.
A rigid underwater case would be ideal, but the good ones are quite expensive and even they might get damaged. It may be more sensible to rent one, if you can find a place that offers one to fit your particular camera and lens. However, most cases can't accomodate longer telephotos... and lens changes, even memory card or battery changes are a pain in the arse.
Oh, and one also has to consider the lenses being protected... What's it cost to replace an 18-55 or 75-300? Around $120 each? Is a $45 protection filter a good investment for either? Canon hood is another $25 or so (there are cheaper 3rd party clones) but would always be a good idea to have and use anyway. It would cost upwards of $300 or $400 to rent an underwater housing with a couple lens ports, so would be cheaper to replace both those lenses if they get damaged.
The most practical "protection" of all might be an insurance overrider covering the gear against damage, with no deductible.